Database Overview

Database Overview:

A database is a collection of organized and structured data, stored in the computer as files. Various data types like numeric, textual, image, multimedia etc., can be managed and maintained more efficiently in a database.

Database Types:

• Database Management Systems (DBMS)
• Relational Database Management Systems (RDBMS)
• Object Oriented Databases
• Multidimensional Databases

Often used databases (RDBMS) in most of the practical applications are Oracle, Sql Server, Informix, Teradata, DB2 etc., and in the following pages, Oracle’s data structures are used as examples to explain the relationship between data modelling and database. In order to design a data model in a proper manner, a data modeler has to know the different objects (data structures) present in a database. Also data modeler should have a sound knowledge of the data present/to be present in the database, should be able to design a data model using a data modelling tool like Erwin, and to generate DDL scripts from the Data Modelling tool.

Given below is the list of Oracle data objects and in the following pages, a brief overview is given for each of these objects.

Oracle Database Objects:

• Instance
• Schema
• Table
• Column
• Data type
• Primary Key Constraint
• Unique Constraint
• Check Constraint
• Null
• Not Null
• Index
• Sequence
• View
• Materialized View
• Synonym
• Procedure
• Function
• Package
• Trigger